Police label Baulkham Hills attack 'bad as it gets'

NSW Police have set up a strike force to investigate the abduction and sexual assault of a woman in Baulkham Hills.

Police confirmed the 18-year-old was walking home along Merindah Road from a house party early on Sunday morning when she was stopped, near St Michaels Place, by a group of men in a green sedan asking for directions.

The woman gave directions and continued walking. She was then grabbed and thrown into the back of the car where she was taken to an unknown location and sexually assaulted.

She was later dumped in Waterloo Avenue in Castle Hill. The victim reported the matter when she got home and was taken to Westmead Hospital.

NSW Commander of the Sex Crimes squad Detective Superintendent John Kerlatec said the attack was a "traumatic experience" for the victim and "every woman should be able to walk Sydney streets without fear".

"I'd encourage women where possible to walk with a friend and don't get too close to people asking for directions, and walk in well lit streets," he said.

At this stage it's not yet confirmed whether the offenders were at the same house party as the victim.

Detective Superintendent Kerlatec said it was too early to say whether the incident was opportunistic or planned.

The man in the front passenger seat who asked for directions has been described as being about 25-years-old, of Caucasian appearance, with a chubby build and a beard. He was wearing a red and white flannelette shirt.